I have had Lily, my pug, since she was 2 months old, she is now 7 1/2 years. She and I are together most of the time. Ana Grey, almost 5 months, I have had for three weeks. Ana's breeder had 2 small dogs so she was use to dogs, in fact could yelp like a small dog when I first brought her home. If Ana Grey lands on the floor Lily will bark to let me know Ana is on the floor, she use to run to Ana but since I always said "no you leave her alone" she no longer runs to her just barks. If Ana lands on Lily's bed, Lily ignores her, I immediately remove Ana and tell her "no, Ana leave Lily along". Not because I am afraid for Ana, but because I am afraid for Lily. Lily has huge eyes and if Ana should bite at one of her eyes, well we won't go there. If I am going to leave the room I put Ana back in her cage, after all they are both still animals and I am responsible for both of their wellbeings. They are equally reprimanded for invading the other's space.
When family are over, both pets are equally fawned over because it would be easy for Lily to become jealous and I know her well enough to be very aware of this. I hope this helps.